:root{
  --page:#eceff5; --card:#fff; --line:#e3e6ee; --text:#111827; --body:#4b5563; --muted:#6b7280;
  --blue:#2563eb; --blue-dark:#1d4ed8; --tint:#f2f5fb;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:84px}
@media (prefers-reduced-motion:reduce){html{scroll-behavior:auto}}
body{margin:0;padding:0;background:var(--page);color:var(--body);
  font:15px/1.7 Inter,system-ui,-apple-system,"Segoe UI",Roboto,"Helvetica Neue",sans-serif;-webkit-font-smoothing:antialiased}
a{color:var(--blue)}
a:focus-visible{outline:2px solid var(--blue);outline-offset:3px;border-radius:4px}

.frame{max-width:1120px;min-height:100vh;margin:0 auto;background:var(--card);overflow:hidden}

/* nav */
.nav{position:sticky;top:0;z-index:10;display:flex;align-items:center;justify-content:space-between;gap:24px;
  height:60px;padding:0 40px;background:rgba(255,255,255,.9);backdrop-filter:blur(10px);-webkit-backdrop-filter:blur(10px);border-bottom:1px solid #eef0f5}
.logo{display:flex;align-items:center;gap:8px;color:var(--text);font-weight:700;font-size:15px;text-decoration:none;letter-spacing:-.01em;white-space:nowrap}
.logo svg{width:22px;height:22px}
.links{display:flex;align-items:center;gap:28px}
.links a{color:#1f2937;font-size:13.5px;text-decoration:none;white-space:nowrap}
.links a:hover{color:var(--blue)}
.links a.btn{background:var(--blue);color:#fff;font-weight:600;padding:8px 16px;border-radius:8px;transition:background .15s}
.links a.btn:hover{background:var(--blue-dark);color:#fff}

/* header */
.head{padding:32px 56px 36px;background:linear-gradient(180deg,var(--tint),#fff)}
.back{display:inline-block;font-size:13px;text-decoration:none;margin-bottom:14px}
.back:hover{text-decoration:underline}
h1{margin:0 0 6px;font-size:clamp(1.9rem,4vw,2.4rem);line-height:1.15;letter-spacing:-.025em;color:var(--text);font-weight:700}
.updated{margin:0;color:var(--muted);font-size:13.5px}

/* body */
.body{display:grid;grid-template-columns:minmax(0,1fr) 400px;gap:48px;padding:12px 56px 72px;align-items:start}
.text{max-width:580px}
.text p{margin:0 0 14px}
.text h2{margin:34px 0 10px;font-size:1.05rem;line-height:1.3;color:var(--text);font-weight:700;letter-spacing:-.01em}
.text strong{color:var(--text);font-weight:600}
.text ul,.text ol{margin:0 0 14px;padding-left:22px}
.text li{margin-bottom:7px;padding-left:2px}
.text li::marker{color:var(--muted)}

.art{position:sticky;top:96px}
.art svg{display:block;width:100%;height:auto}

/* footer */
.foot{display:flex;justify-content:space-between;flex-wrap:wrap;gap:8px;padding:20px 56px;border-top:1px solid var(--line);color:var(--muted);font-size:13px}

@media (max-width:900px){
  body{padding:0}
  .frame{border-radius:0;border:0}
  .nav{padding:0 20px}
  .links a:not(.btn){display:none}
  .head{padding:24px 24px 28px}
  .body{grid-template-columns:1fr;gap:24px;padding:8px 24px 48px}
  .art{position:static;max-width:360px;margin:0 auto}
  .foot{padding:20px 24px}
}